Actually known methods for changing the frequency of the generated radiation of a laser resonator are based on an exchange of resonator mirrors or on the effect of a dispersion element within the resonator. In both cases, an accurate adjustment of optical elements is required. In the case of dispersion elements, for example, prisms are used and high requirements on the accuracy of their adjustment are made.
The more elements the resonator contains, the larger losses of efficiency of generated radiation are experienced, the adjustment is more complicated and in addition results in a rather unacceptable length of the resonator.
It is an object of this invention to provide a laser resonator where changes of the frequency of generated radiation can be achieved by simple means avoiding the disadvantages of the known methods.